For the past five years, the Belgian conceptual artist Wim Delvoye has been building machines that mimic the human digestive system. Each of the four so-called cloaca devices is a room-filling, Heath Robinson-style assemblage of tubes, beakers and electric pumps that produces a realistic approximation of human faeces.

Now Delvoye has issued 100 bonds, each priced at 3,000 euros, that can be redeemed in three years' time, either for cash or for vacuum-packed artificial turds.

His original aim with the bond issue, he says, was to recreate the craze of the dotcom boom. Because of the three-year delay, holders have a limited period in which to trade their bonds. "After the first year, the anxiety will start," he says. "The anxiety between art and life. Between monetary and symbolic value."

Interested parties must travel to Delvoye's studio in Belgium before November. That might seem like a lot of effort for what is, in effect, a turd voucher, but according to Delvoye the bonds are selling fast.